Ionic liquids are essentially salts in a liquid state, and are described in U.S. Pat. Nos. 4,764,440, 5,104,840, and 5,824,832. The properties vary extensively for different ionic liquids, and the use of ionic liquids depends on the properties of a given ionic liquid. Depending on the organic cation of the ionic liquid and the anion, the ionic liquid can have very different properties. The behavior of the ionic liquid varies considerably for different temperature ranges, and it is preferred to find ionic liquids that do not require operation under more extreme conditions such as refrigeration.
Ionic liquids have been used to catalyze a variety of hydrocarbon conversion processes, such as alkylation, isomerization, disproportionation, and the like. When ionic liquids are used to catalyze hydrocarbon conversion processes, the ionic liquid catalyst is typically dispersed into droplets to provide intimate contact between the various reactants. The mixture of ionic liquid, reactants and products are typically separated by gravity into two phases, a heavier ionic liquid phase and a lighter hydrocarbon phase. It is common for the hydrocarbon phase to include fine droplets of ionic liquid. As a result of the relatively high cost of ionic liquids, it is generally desirable to recover this entrained ionic liquid.
Conventional separation vessels comprise horizontally disposed vessels that allow the effluent to settle into the two phases and typically use coalescing medium or other elements to try and remove and/or recover the entrained droplets of ionic liquid contained within the hydrocarbon phase. While these conventional separation vessels and methods are believed to be effective for their intended purposes, there may be drawbacks associated with same.
For example, the horizontal vessels require a relatively large amount of plot space given the required time necessary for separating the effluent into the two phases. While this may not be a drawback for all applications and uses of such separation vessels, some locations may lack the requisite space for such vessels. Additionally, a coalescing media, which is typically required to remove the entrained ionic liquid from the hydrocarbon phase, may become fouled or plugged over time. This may impact the flow of fluids there through, as well as require maintenance or repairs to address—which requires equipment or unit shutdown resulting a loss of production and increased costs.
Accordingly, the present invention is directed at providing a separation vessel that addresses one or more of these drawbacks associated with the conventional separation vessels used for separating an effluent having ionic liquid.